ruby · makenowjust · Jan 10, 2024 · Jan 9, 2024
diff --git a/regexec.c b/regexec.c
@@ -3758,14 +3758,15 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
     CASE(OP_PUSH_IF_PEEK_NEXT)  MOP_IN(OP_PUSH_IF_PEEK_NEXT);
       GET_RELADDR_INC(addr, p);
+      CHECK_MATCH_CACHE;
       if (*p == *s) {
 	p++;
-	CHECK_MATCH_CACHE;
 	STACK_PUSH_ALT(p + addr, s, sprev, pkeep);
 	MOP_OUT;
 	JUMP;
       }
       p++;
+      INC_NUM_FAILS;
       MOP_OUT;
       JUMP;
 

diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
@@ -1945,6 +1945,15 @@ def test_match_cache_negative_look_behind
     end;
   end
 
+  def test_match_cache_with_peek_optimization
+    assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}")
+    timeout = #{ EnvUtil.apply_timeout_scale(10).inspect }
+    begin;
+      Regexp.timeout = timeout
+      assert_nil(/a*z/ =~ "a" * 1000000 + "x")
+    end;
+  end
+
   def test_cache_opcodes_initialize
     str = 'test1-test2-test3-test4-test_5'
     re = '^([0-9a-zA-Z\-/]*){1,256}$'